Patent GB-900481-A (GB)
Title: Improvements in or relating to printing apparatus
Inventor: WOODHEAD JAMES
Filed: 1957-09-25
Abstract: 900,481. Typewriters &c. INTERNATIONAL COMPUTERS & TABULATORS Ltd. Sept. 8, 1958 [Sept. 25, 1957], No. 30081/57. Class 100 (4). A printing apparatus for data received as pulses from record cards or other sources is provided with storage means so that printing occurs during relative movement in either letterspacing direction between one or more printing heads and a record sheet. Either the paper carriage or the printing head may be moved. As shown, a record sheet 14 on a platen 15 is continuously reciprocated past a single stationary printing element 45 by a motor 60 and a roller chain 19. The position of the carriage relative to the printing element is sensed by a photo-electric cell 22 as it scans a graticule 20 and a pulse is fed to a position indicator 6 which in this case is a counter which adds the pulses as the carriage moves in one direction and substracts them in the other so that the stage which is conducting at any instant corresponds to a particular position of the record sheet being opposite the printing head. A photo-electric cell 23 receives a pulse at each end of the carriage movement which by a trigger 25 acts as a limit switch reversing the movement of the carriage, causes line spacing, and changes over gates 26, 27 so that the direction of counting in the position indicator 6 is reversed. A programme device 7 comprises stages 31 corresponding to the stages of the indicator 6 but separate from each other. Those stages corresponding to positions where printing is required are rendered conductive by plugable connectors 33 connecting appropriate sockets 32 to a common line 35. When a conducting stage of the indicator 6 corresponds with a conducting stage of the programme device 7 a pulse is passed by a comparing unit 8 to open a gate 57 to allow a pulse from the photo-electric cell 22 to be passed through a gate 41 or 42 to a distributer 39 to a matrix storage 38 in which a line of information has been stored. The pulses passed over a line 37 and through a gate 41 or 42 cause the stages of the distributer 39 to conduct sequentially in synchronizm with the stages of the indicator 6 to allow the stored information to be read out to a de-coder 4 to cause the printer head 45 to operate. Other types of static storages may be used such as electronic trigger storages or neon tubes. By suitable arrangement of the plugable connectors 33 printing can be started and restricted to certain portions of the line to provide for tabulation or like operations. The photo-electric cell carriage position indicator may be replaced by indicators dependent on the closing of contacts by cams on the carriage or the sensing of commutator segments associated with the carriage as described in Specification 879,988. The printer head may alternatively be in the form of type wheels or bars carrying type characters. A plurality of printer heads may be provided, controlled by a single distributer 39, to increase the printer speed, the heads being arranged at spaced intervals on a single line so that the carriage movement to complete a line of printing is reduced or in different lines so that a plurality of lines are printed simultaneously, followed by a multiple of line spacing. If two storage sections are provided for each printer head the printing is speeded as data can be read in and out simultaneously. In a completely modified arrangement a constantly rotating magnetic storage drum is employed with a modified control system which ensures that data is read out in the desired position.. The apparatus allows data derived from one or more record cards or other sources to be printed in a different arrangement to that in which it was recorded. Specification 796,685 also is referred to. Reference has been directed by the Comptroller to Specification 819,466.